What Does Mono Do to Your Body?

Medically Reviewed on 2/16/2022
Mononucleosis can lead to symptoms such as fever, sore throat, fatigue, headache, swollen lymph nodes, and rash.

Mononucleosis can lead to symptoms that develop gradually, within four to six weeks (incubation period) after the person is infected with Epstein–Barr virus, and may result in the following:

What causes mononucleosis?

Mononucleosis (mono) is an infectious viral disease caused by Epstein–Barr virus (EBV) although other viruses can cause the disease too.

Once a person is infected with mono, it is very unlikely that they get the infection again. They will remain immune to the virus for the rest of their life.

Symptoms typically resolve within two to four weeks of infection. However, the virus may remain dormant in the throat and body fluids for the rest of your life and may reactivate periodically with no obvious symptoms. Thus, a person can pass on the disease to others despite being asymptomatic.

Is mono contagious?

Mononucleosis is a contagious disease (spreads from person to person) that predominantly affects teenagers and young adults.

  • Mononucleosis is also called “kissing disease” because the virus is present in the saliva and is easily and often transmitted by kissing.
  • It can be transmitted by sneezing and coughing, as well as sharing glasses, cups, straws, or anything else with saliva on it.
  • Other body fluids such as blood (transfusions) and semen (through sexual contact) and organ transplantations can transmit the infection.

How is mononucleosis diagnosed?

Infectious mononucleosis is typically diagnosed based on the symptoms presented by the infected person.

Your doctor may recommend the following to judge the severity of infection:

Although not recommended routinely, certain laboratory tests (antibodies to Epstein–Barr virus [EBV]-associated antigens) can help distinguish recent or past infections.

  • Anti-viral capsid antigen (VCA) antibody test:
    • Anti-VCA IgM: Typically appears in the early phase of EBV infection and disappears in four to six weeks after the infection is resolved.
    • Anti-VCA IgG: Initiates to appear in the acute phase, reaches its peak during the illness (four to six weeks), declines gradually, and remains persisting for the rest of the life.
  • Monospot test or heterophile test:
    • Looks for a special type of antibodies called heterophile antibodies that are produced in response to EBV infection
  • EBV nuclear antigen (EBNA):
    • Antibodies to EBNA is confirmed by immunofluorescent test, two to four months after the onset of symptoms, and persist for the rest of life
  • Early antigen (EA):
    • Anti-EA IgG typically occurs in the acute phase of infection (a sign of active infection) and declines to undetectable levels post three to six months of initial infection

9 potential complications of infectious mononucleosis

Very rarely, infectious mononucleosis can lead to complications such as:

  1. Hemolytic anemia
  2. Inflammation of the kidney
  3. Hepatitis (inflammation of the liver)
  4. Jaundice (yellowing of the skin and eyes)
  5. Spleen rupture
  6. Inflammation of the heart
  7. Upper airway obstruction
  8. Dysrhythmia
  9. Nervous system disorders such as meningitis and encephalitis


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Medically Reviewed on 2/16/2022
Image Source: iStock Images

About Infectious Mononucleosis Centers for Disease Control and Prevention: https://www.cdc.gov/epstein-barr/about-mono.html

Infectious Mononucleosis Johns Hopkins Medicine: https://www.hopkinsmedicine.org/health/conditions-and-diseases/infectious-mononucleosis

Infectious mono Doctors of Osteopathic Medicine: https://findado.osteopathic.org/infectious-mono-kissing-disease

Mononucleosis Cleveland Clinic: https://my.clevelandclinic.org/health/diseases/13974-mononucleosis